The subject of the present invention is a suspension device for tire carcasses; more precisely, the invention relates to a suspension device for holding uncured carcasses during manufacture of the tires, keeping their axes vertical. Hereinafter, this type of suspension will be designated by the expression xe2x80x9cvertical suspensionxe2x80x9d.
It is known that current manufacture of radial-carcass tires can be carried out in several stages: first of all, on what is called a xe2x80x9cfirst-stagexe2x80x9d machine, or alternatively a xe2x80x9cbuildingxe2x80x9d machine, on which the carcass proper is constructed from bead wires and a cylinder of uncured rubbers which is shaped to make it toroidal; then, on what is called a xe2x80x9csecond-stagexe2x80x9d machine, or alternatively a xe2x80x9cfinishingxe2x80x9d machine, on which a cylindrical crown reinforcement, or belt, and a tread are applied to this carcass; finally, the entire unit is vulcanised in a mold.
In this method of manufacture, between the two main stages described above, it is necessary to store or possibly transport the uncured carcass from the building machine to the finishing machine, in a state in which it is highly deformable, since the rubber is in the plastic, non-vulcanised, state. Formerly, the carcasses were attached to brackets, the axes of the carcasses being horizontal, but, under the effect of their own weight they became deformed into an oval; then the carcasses were laid flat, their axes being vertical. However, with the increase in the weight of tires, it was noted that the upper sidewall sags.
Devices were therefore conceived of to avoid this deformation. Thus U.S. Pat. No. 4,452,655 describes a support means for an uncured tire carcass comprising two beads, with its axis vertical. This elliptical support means comprises four vertical plates capable of accepting a certain elastic flexion which enables them to engage beneath the upper bead in order to hold the carcass, the plates being distributed over the two minor arcs of the ellipse.
The carcass is thus held on the support by the plates bearing against said carcass beneath the upper bead, the carcass opposing radial extension of the plates. The thrust forces exerted on the carcass, which are irregularly distributed over the circumference of the carcass owing to the elliptical shape of the support means, risk causing deformation of the carcass.
Furthermore, the support means, in order to be able to accept carcasses of different dimensions, utilizes the flexibility of the plates, which indicates that carcasses of smaller dimensions are subject to greater stresses and hence greater risks of deformation. In order to avoid this phenomenon, each tire dimension requires a corresponding size of the device, which is therefore no longer multidimensional.
Finally, the operation of unloading the carcass is complicated, and cannot be automated. In fact, it is necessary to displace the carcass transversely and tilt it in order to disengage one of its sides, then to bring it back in the opposite direction in order to disengage the other side and thus free the whole carcass.
Note that xe2x80x9ccarcassxe2x80x9d designates the raw blank that results from the operations performed in the first stage.
The present invention is directed at overcoming all these disadvantages.
In order to do this, the invention proposes a device for the substantially vertical suspension of tire carcasses, comprising a plurality of articulated supports mounted on a handling plate comprising a longitudinal axis XXxe2x80x2 around which are distributed the supports, the latter being able to bear on the inside of a tire carcass, each of said supports also comprising a convex bearing surface of given length, each of the supports being able to adopt a plurality of angular positions, such that for each given angular position there corresponds a different radial distance between the points of said bearing surfaces which are radially farthest from the longitudinal axis XXxe2x80x2.
Such an arrangement permits the insertion, according to the angular positions of the bearing surfaces and hence of the radial distance between the opposed surfaces, of carcasses of a whole range of dimensions. It is not necessary to change the support, or any other element. It is therefore possible to pass from one dimension to another very rapidly and with very great ease.
Advantageously, taking as a reference the orientation of the forces of gravity, the supports and the bearing surfaces are arranged such that, at least when in the engaged position on the carcass, the points of contact between the carcass to be suspended and the supports are located above the axes of rotation of the supports. Thus, if any force tends to draw the carcass downwards, owing to the relative position of the pivot point, the action of the force tends to spread the supports apart, which increases the holding force thereof. This makes it possible, for example, to minimize the risk of accidental falling.
Preferably, a stop is able to define the axial position of the carcass to be suspended, so as to determine the location on the carcass where the bearing surfaces exert their gripping force. Preferably, this location is substantially at the level of the upper bead of the carcass. The stop is advantageously arranged so as to act in the normal axial path of travel of the carcass to be inserted.
Advantageously, the supports comprise a second, cam-shaped part which serves to control the positioning of the bearing surfaces. It is thus possible to control the positioning of the supports automatically or semi-automatically.
Advantageously, provision is also made for simultaneous bringing-together of the arms, which makes it possible to achieve a retracted position of the arms in which the latter are no longer in contact with the carcass, which permits easy and simple unloading of said carcass.
According to an advantageous variant, each support comprises a first and a second part, each axis of rotation being mounted between said first and second parts. The first part of each support is curved and bears the bearing surface on its convex side.
According to an advantageous characteristic of the invention, the actuating means comprise:
a first member which controls the rotational movement of all the supports simultaneously in the sense of bringing together the bearing surfaces of the vertical axis, and formed by a movable plate which is mounted to slide about the vertical axis and bearing projections which cooperate respectively with the second part of each support by exerting a vertical thrust on the latter,
and second members controlling the rotational movement of the supports in the opposite direction and formed by springs mounted respectively on the axes of rotation of the supports.
The displacement of the movable plate which, by its thrust action on the supports, makes it possible to permit unloading of the carcass, is actuated manually by means of a rod or automatically remotely by means of a control piston-cylinder unit.
Other characteristics and advantages of the invention will become apparent on reading the examples of embodiment of the suspension device for tire carcasses according to the invention, which are given in non-limitative manner, with reference to the appended drawings.